Here's a pic of the '43 turret, the sticking up bit with the little hole on the front at the front left is the gun's panoramic sight, it's the model that can be used to aim the gun aswell. The gunner/commander also has another panoramic sight on this model ontop of his 85 style cupula this model can't aim the gun and replaced all station's panoramics on the 85 model. The blob on the back is the air vent.
Here's a captured '41 model, it's been fitted with another panoramic sight of the same model for the loader but it would just be used for observation. Most of them didn't have the second sight fitted but there's a space where it could go. The bump in the middle is the air vent.